Referring to FIG. 1, a radio network involved in cell handover in the prior art includes a Radio Network Controller (RNC) 110, nodes (NODEB, i.e. base stations of a WCDMA system) 120 and User Equipments (UEs) 140 attached to the nodes 120. When a UE 140 is handed over between cells 130, relevant information is added by a node 120 in a RADIO LINK ADDITION (RL ADDITION) signaling process to inform the RNC 110.
Referring to FIGS. 1 and 2, an example of handover in the prior art, i.e. a process of switching Dedicated CHannel/Enhanced UpLink (UL) Dedicated CHannel (DCH/E-DCH) traffic between cells 130 includes the following steps.
201: At stage 1, the UE 140 establishes Radio Link (RL) 0 in CELL0 (CELL is a logic cell in the case of a WCDMA system) of NODEB0 through a signaling process for radio link establishment. CELL0 supports both DCH and E-DCH traffic. The specific traffic borne on RL0 is 3.4K+64K (downlink only)+High Speed Uplink Packet Access (HSUPA), in which the DCH traffic refers to 3.4K+64K (downlink only), and the E-DCH traffic refers to HSUPA.
202: At stage 2, the UE 140 moves to the common coverage area to CELL0 of NODEB0 and CELL1 of NODEB1 and establishes RL1 in CELL1 of NODEB1 through a signaling process for radio link establishment. CELL1 supports only DCH traffic. In this case, the specific traffic borne on RL1 is DCH: 3.4K+64K (downlink only). At this point, the UE 140 has two radio links RL0 and RL1, on which DCH data are subjected to soft combining at NODEB1. The soft combining here means that a radio link is selected at the side of the RNC 110.
203: As the UE 140 continues to move at stage 3, the UE 140 adds RL2 in CELL2 of NODEB1 through a signaling process for radio link establishment. CELL2 supports DCH and E-DCH traffic. The process for the addition includes the following.
a: CELL2 and the UE 140 detect signals for themselves respectively.
b: CELL2 and the UE 140 report the respective detection results to the RNC 110 via NODEB1.
c: The RNC 110 sends to NODEB1 a request for adding RL2.
d: NODEB1 adds RL2 and informs the RNC 110 of the link establishment result via an RL ADDITION signaling process, and the RNC 110 performs communication control according to the link establishment result.
204: As the UE 140 continues to move at stage 4, the signals for the UE 140 in CELL0 and CELL1 become so weak that the RNC 110 may delete RL0 and RL1 and only one radio link RL2 remains for the UE 140.
In the above step 203, because CELL2 supports DCH and E-DCH traffic and CELL0 also supports E-DCH traffic, the RNC 110 may request NODEB1 for bearer of E-DCH traffic on the newly added RL2, thereby enabling continuation of the traffic. Therefore, the specific traffic borne on RL2 is 3.4K+64K (downlink only)+HSUPA. At this point, the UE 140 has three radio links RL0, RL1 and RL2. RL0 is subjected to DCH soft combining with RL1 and RL2 respectively. RL1 and RL2 are subjected to DCH softer combining. The softer combining here means that the radio links are combined at the side of a NODEB into one link for sending the data to the RNC 110.
In general, only the softer combining of the links and the new establishment/new addition of DCH/E-DCH need to be informed to the RNC 110 via an RL ADDITION signaling process. The RNC 110 directly handles the soft combining in which a link is selected between the two NODEBs. The softer combining in which the links are combined at one NODEB needs to be presented in RL ADDITION signal by the NODEB. Likewise, the new establishment/new addition of DCH/E-DCH which is also implemented at one NODEB, needs to be presented in RL ADDITION signal by the NODEB.
Referring to Table 1, in sub-step d of step 203, information of the new establishment of E-DCH traffic and information of the softer combining of DCH traffic are informed to the RNC 110 in a RADIO LINK ADDITION RESPONSE message sent from NODEB1 to the RNC 110.
TABLE 1Schematic structure of RADIO LINK ADDITION RESPONSE messageIE Type andSemanticsAssignedIE/Group NamePresenceRangeReferenceDescriptionCriticalityCriticality. . .. . .. . .. . .. . .. . .. . .RL Information1 . . . <maxnoofRLs-1>EACHignoreResponse>RL IDM9.2.1.53—>RL Set IDM9.2.2.39—>Received Total WideM9.2.2.39A—Band Power>CHOICE DiversityM—Indication>>Combining—>>>RL IDM9.2.1.53Reference—RL>>Non Combining—>>>DCH InformationM9.2.1.20C—Response>>>E-DCH FDDO9.2.2.13DbYESignoreInformation Response>SSDT SupportM9.2.2.46—Indicator. . .. . .. . .. . .. . .. . .. . .E-DCH Serving CellO9.2.2.18EdYESIgnoreChange InformationResponse
1. For the new establishment of E-DCH traffic, Non Combining corresponding to E-DCH Frequency Division Duplex (FDD) Information Response information needs to be selected in a CHOICE Diversity Indication field of the RADIO LINK ADDITION RESPONSE message sent from the NODEB1 to the RNC 110, so that the RNC 110 understands that a link on which E-DCH traffic runs needs to be established for the UE 140.
2. For the softer combining of DCH traffic, Combining corresponding to an RL Identifier (ID) needs to be selected in the CHOICE Diversity Indication field, so that the RNC 110 understands that softer combining of the DCH needs to be implemented for the UE 140.
In Information Element (IE) column in the above Table 1, the symbol “>” represents a first level field, the symbol “>>” following the symbol “>” represents a second level field subordinate to the first level field, and the symbol “>>>” represents a third level field corresponding to the second level field. For the CHOICE Diversity Indication field, two second level fields, Combining and Non Combining, are provided, to which third level fields, RL ID and DCH Information Response, are subordinate respectively. The Combining field is used to inform the RNC of the softer combining, and the Non Combining field is used to inform the RNC of the new establishment/new addition of DCH/E-DCH.
For a RADIO LINK ADDITION RESPONSE message, only one second level field, i.e. Combining or Non Combining, can be selected in the CHOICE Diversity Indication field. In other words, only one entry, Combining or Non Combining, can be selected in the CHOICE Diversity Indication field, in the case of which the CHOICE Diversity Indication field would be erroneous no matter how the CHOICE Diversity Indication field is filled.
Because in step 204, as the UE 140 continues to move at stage 4, the signals of the UE 140 in CELL0 and CELL1 become so weak that the RNC 110 may delete RL0 and RL1 and only one radio link RL2 remains for the UE 140.
In this case, if Combining is selected in the CHOICE Diversity Indication field in step 203, the E-DCH FDD Information Response information can not be informed to the RNC because only one entry can be selected in the CHOICE Diversity Indication field. At stage 4, the HSUPA traffic corresponding to E-DCH for the UE 140 is therefore interrupted. If Non Combining is selected in the CHOICE Diversity Indication field in step 203, the NODEB1 can not fill the DCH Information Response IE, resulting in failure of NODEB1 to add RL2. At stage 4, therefore, no radio link is available for the UE 140 and the entire traffic for the UE 140 is interrupted.
In another case, the above step 203 may be 203′, referring to FIGS. 3 and 4.
203′: As the UE 140 continues to move at stage 3, the UE 140 adds RL2 in CELL2 of NODEB1 successfully through a signaling process for radio link establishment and tries to add RL3 in CELL3 of NODEB1 through a signaling process for radio link establishment but fails. CELL2 supports DCH and E-DCH traffic, and CELL3 may be a cell that supports any traffic, for example, only DCH or E-DCH traffic, or possibly both DCH and E-DCH traffic. The process for the successful addition of RL2 and failed addition of RL3 includes the following.
a: CELL2, CELL3 and the UE 140 detect signals for themselves respectively.
b: CELL2, CELL3 and the UE 140 report the respective detection results to the RNC 110 via NODEB1.
c: The RNC 110 sends to NODEB1 a request for adding RL2 and RL3.
d: NODEB1 adds RL2 successfully but fails to add RL3 and informs the RNC 110 of the link establishment result via a RADIO LINK ADDITION FAILURE message as shown in Table 2, instead of the RADIO LINK ADDITION RESPONSE message as shown in Table 1. The RNC 110 performs communication control according to the link establishment result.
TABLE 2Schematic structure of RADIO LINK ADDITION FAILURE messageIE Type andSemanticsAssignedIE/Group NamePresenceRangeReferenceDescriptionCriticalityCriticality. . .. . .. . .. . .. . .. . .. . .CHOICE Cause LevelMYESignore>General—>>CauseM9.2.1.6—>RL Specific—>>Unsuccessful RL1 . . . <maxnoofRLs-1>EACHignoreInformation Response>>>RL IDM9.2.1.53—>>>CauseM9.2.1.6—>>Successful RL0 . . . <maxnoofRLs-2>EACHignoreInformation Response>>>RL IDM9.2.1.53—>>>RL Set IDM9.2.2.39—>>> Received TotalM9.2.2.39A—Wide Band Power>>>CHOICE DiversityM—Indication>>>>Combining—>>>>>RL IDM9.2.1.53Reference—RL>>>>Non Combining—>>>>>DCHM9.2.1.20C—Information Response>>>>>E-DCH FDDO9.2.2.13DbYESignoreInformation Response>>>SSDT SupportM9.2.2.46—Indicator. . .. . .. . .. . .. . .. . .. . .
In Table 2, for the Successful RL Information Response field, a CHOICE Diversity Indication field is provided subordinate thereto, which is identical to that in Table 1 but becomes a third level field, and to which two fourth level fields, Combining and Non Combining, are subordinate. For the two fourth level fields, fifth level fields, RL ID and DCH Information Response and E-DCH FDD Information Response are provided subordinate thereto respectively. The Combining field is used to inform the RNC of the softer combining, and the Non Combining field is used to inform the RNC of the new establishment/new addition of DCH/E-DCH.
Likewise, for a RADIO LINK ADDITION FAILURE message, only one fourth level field, i.e. Combining or Non Combining, can be selected in the CHOICE Diversity Indication field. In other words, only one entry, Combining, or Non Combining, can be selected in the CHOICE Diversity Indication field, in the case of which the CHOICE Diversity Indication field would be erroneous no matter how the CHOICE Diversity Indication field is filled. This is for the same reasons as stated with respect to the RADIO LINK ADDITION RESPONSE message.
The process of switching DCH/E-DCH traffic between cells for a UE in the prior art is not limited to the above scenarios. The above problems may occur when softer combining needs to be implemented and establishment of relevant traffic needs to be reported to an RNC. In other words, a NODEB can not inform the RNC correctly of information of a link for a current user due to the deficiency in the structure of the RADIO LINK ADDITION FAILURE message, resulting in an error in signaling processing at the IUB interface (an interface between the RNC and the Node B).